In an essay for college newspaper The Daily Iowan, where she works as a photographer, Mitchell described her experiences as "a spontaneous moment leading to an unplanned life change. Not a mistake. Definitely a surprise." Her photo-essay and videos have had a powerful impact around the world. (You can see her entire slideshow here.)

According to the essay, she found out she was pregnant on March 25, 2012. She and her boyfriend decided to have the child and begin a new chapter in their life together.

Read on to learn how Callie felt via her intimate journal entries.

"I was excited at the thought of being a mom and loving my own child," she writes in the essay, which reads like a series of intimate journal entries. "I had the perfect boyfriend who I was in love with, and we had talked about getting married and having children someday — someday just came sooner than we expected."

Just six weeks later, though, her boyfriend left her. She had been unfaithful, and he found out. "It's no one's fault but my own. The lies had caught up with me, and he couldn't stand the thought of raising a baby that might not be his," she writes. "He couldn't start a family with a girl that gave him every reason not to trust her. I've never hated myself so much in my entire life."

He wanted her to give the child up for adoption — "Abortion was never an option, in my mind," she explains — but she struggled with the decision. "I can't carry a child for nine months, feel it grow, and feel it kick," she writes. "I can't have a baby be a part of me and give it up. I can't give up a piece of me. I can't give birth, be in labor for hours, and feel the pain of my baby. I can't give all of that love and just give it away like nothing happened."

It would be months before she made up her mind.

As she deliberated, she decided to document everything about her pregnancy, photographing her growing baby bump and recording her thoughts. She wove her story into a compelling video-diary-and-photo essay for The Daily Iowan, pointing out, "This is my baby, but he's not my child."

She left her job as a waitress, kept her job as a photographer for The Daily Iowan, and stayed in school. She decided to give the baby up for adoption, and worked with an agency to pick the birth parents, prompting her to face issues she had never even thought about before. While at lunch with the adoptive-mother-to-be, they discussed whether Mitchell would even hold the baby once he was born.

"I said no, I wanted the first person to hold him to be his parents because that first touch is so important," she writes. "It is the first and most powerful moment when a bond is formed between parent and child, and I didn't want to steal that from Kristen and Brian. I was also terrified of getting too attached to him and then not being able to handle it when he is gone."
"One of the first things people say to me after hearing my story is that I'm a strong person. I'm not strong. I've never been a strong person," she writes. "People who haven't gone through this heartbreak don't understand the helplessness you feel, the loss."

Her story has a happy ending: The adoptive parents, who live in Ohio, are enthusiastic about keeping in touch.
"Kristen and I talk at least once a day," Mitchell writes when the baby, whom she named Leo, is almost 3 months old. "She tells me about their lives, and I keep her updated on things going on in my life. She sends me at least one picture of Leo almost every day." She has plans to visit Leo in March; she and Kristen are going to get matching tattoos in honor of the boy they call "our son."

"At first, I thought I had made a mistake and that I should have my son with me," Mitchell confesses. "I cried a lot for the first month he was gone. Even now, I cry every once in a while because I miss him."

But "in all honesty, this is the best thing I could have done for my son, and I did it completely out of love for him," she continues. "He now has the perfect parents that give him so much love. I have no doubt they will raise him to be the best person he can be, and they will also be able to provide him with every opportunity to reach any goal he has for his life. I'll always be there. I'll always be involved and always be cheering him on and loving him from a distance."